Certain internal combustion engines comprise multi-valve cylinders. In such an engine more than one intake valve and/or more than one exhaust valve per cylinder are present. Because a pair of exhaust valves for a cylinder or a pair of intake valves for a cylinder typically operate concurrently, a known valvetrain comprises a bridge between the valves of each such pair.
A lobe on a rotary camshaft periodically opens a pair of valves in unison via a lifter and pushrod acting on one end of a rocker that is mounted on the engine head to rock back and forth about an axis. The opposite end of the rocker acts on the valves via the bridge and an associated pivot foot.
When the cam lobe moves the pushrod upward, the rocker rocks, causing the pivot foot to act on the bridge and force the valves open, consequently opening the cylinder for intake flow in the case of intake valves or for exhaust flow in the case of exhaust valves.